Class Presentation on Mine Ventilation Network Analysis.

1. University Of Liberia
College Of Engineering
Department Of Mining Engineering
Ventilation Network Analysis
Presented By: Abraham H. Barry
ID#70800
Presented To: Shri Adolphus M. G. D.
Gleekia

2. Ventilation Network Analysis
Presentation Content:
 Introduction and Overview
 Kirchhoff's laws
 Square law in Network analysis
 Analytical methods
 Numerical methods
 Hardy Cross Method
 Conclusion
 References
 Q&A

3. Ventilation Network Analysis
 Introduction and Overview
 Fundamentally the application of the principles of
Fluid dynamics and Thermodynamics

4. Ventilation Network Analysis
 Introduction and Overview
 Fundamental component in the design of a new
underground mine or other subsurface facility
 Ventilation network analysis aids:
 Quantified planning of the circulation of airflows
 Identification of locations and duties of fans
 Establishment of tolerable environmental
conditions

5. Ventilation Network Analysis
 Introduction and Overview
Questions Ventilation Analysis answer:
 What Is the behavior of airflows?
 What are the resistances of the branches ?
 What is the best Arrangement for desired results?

6. Ventilation Network Analysis
 Kirchhoff's laws
 Introduced by Gustav R. Kirchhoff
 The same basic relationships that govern the
behavior of electrical current
 Uses the Laws of Conservation of:
 Mass
 Energy
 Most Basic and useful tool in the analysis of
ventilation networks

7. Ventilation Network Analysis
 Kirchhoff's laws
Kirchhoff's first law states that the mass
flow entering a junction equals the mass
flow leaving that junction.

8. Ventilation Network Analysis
 Kirchhoff's laws
 Mathematically Kirchhoff's Law may be stated as:
 Where M is the mass flow of air entering and
leaving junction i.
 Where Q is the Volume flow rate and ρ is the
density.

9. Ventilation Network Analysis
 Kirchhoff's laws
 In subsurface ventilation system, the difference in
air density around any single junction is negligible
 Valuable and useful tool in the calculation and
verification of airflow measurements taken around
a junction.

10. Ventilation Network Analysis
 Kirchhoff's laws
• Kirchhoff's second law states that the algebraic
sum of all pressure drops around a closed path, or
mesh, in the network must be zero.
0

11. Ventilation Network Analysis
 Kirchhoff's laws
 Steady flow energy equation initially for a single
airway.
 Where:
U= air velocity, Z= height above datum,
W= work input from fan, V= specific volume
P= barometric pressure, F= work done against
friction.

12. Ventilation Network Analysis
 Kirchhoff's laws
 Development of the second Law equation:

13. Ventilation Network Analysis
 Square law
 Derived from the basic Chezy-Darcy relationship
 Stated in two forms:
 Rational
 Traditional

14. Ventilation Network Analysis
 Square law
 Used to restate the Kirchhoff's second law in the
form:

15. Ventilation Network Analysis
 Analytical methods
 Equivalent resistances:
 Most elementary methods of analysis.
 Limited value in the analysis of complete
networks.
 Considerable simplification of the schematic of
actual subsurface ventilation systems.

16. Ventilation Network Analysis
 Analytical methods
 Equivalent resistances:

17. Ventilation Network Analysis
 Analytical methods
 Equivalent resistances:
 For a series circuit
 For a parallel circuit

18. Ventilation Network Analysis
 Numerical methods
 A method of successive approximation.
 First proposed by Atkinson in his paper of 1854.
 Impractical until 1960s (Digital computer age)
 Contributor to the numerical method:
• Y. J. Wang
• Professor Hardy Cross
• D. R. Scott
• F. B. Hinsley

19. Ventilation Network Analysis
 Numerical methods
• Hardy Cross Method
• Iterative method

20. Ventilation Network Analysis
 Conclusion
 All ventilation circuits can be rearranged into
either a series or parallel circuit.
 With Kirchhoff’s equations we can determine:
 Airway resistance.
 Total airflow.
 Ventilating pressure.
 Numerical method presents better analytical tool
for the accurate estimation.
 Computer programs run on the ideas introduced
by numerical analysis.

21. Ventilation Network Analysis
 References
• Hartman, H. L., Mutmansky, J. M., Wang, Y. J., & Ramani, R. V.
(1997). Mine Ventilation Circuits and Networks. In H. L. hartman, J. M.
Mutmansky, Y. J. Wang, & R. V. Ramani, Mine Ventilation and Air
Conditioning (Third Edition ed., pp. 240-290). Canada: JOHN WILEY
& SONS, INC.
• MacPherson, M. J. (1993). Ventilation network analysis. In M. J.
MacPherson, Subsurface Ventilation and Environmental Engineering
(pp. 209-275). Virginia, USA: SPRINGER-SCIENCE+BUSINESS
MEDIA, B.V.
• RAMANI, R. V. (1992). MINE VENTILATION. In H. L. Hartman
(Ed.), SME Mining Engineering Handbook (2nd Edition ed., Vol.
Volume 1, pp. 1069-1109). Littleton, Colorado, USA: Society for
Mining, Metallurgy, and Exploration, Inc.

22. Ventilation Network Analysis

23. Ventilation Network Analysis